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Jay Zhuang commented on CASSANDRA-12676: ---------------------------------------- We saw huge performance gain by disabling coalescing on both 2.2.5 and 3.0.10 (about 50% average latency decrease on some clusters). I would suggest to disable it even in 3.0.x. The attachment is test result for 5 nodes cluster with RF=3, quorum write: https://issues.apache.org/jira/secure/attachment/12842470/result.html || coalescing || disabled || timehorizon || | latency mean | 2.5 ms | 3.4 ms (+36%) | | P95 | 3.4 ms | 4.3 ms (+26%) | | P99 | 5.3 ms | 5.8 ms (+9.4%) | > Message coalescing regression > ----------------------------- > > Key: CASSANDRA-12676 > URL: https://issues.apache.org/jira/browse/CASSANDRA-12676 > Project: Cassandra > Issue Type: Bug > Reporter: T Jake Luciani > Labels: docs-impacting > Fix For: 4.0, 3.x > > Attachments: result.html > > > The default in 2.2+ was to enable TIMEHORIZON message coalescing. After > reports of performance regressions after upgrading from 2.1 to 2.2/3.0 we > have discovered the issue to be this default. > We need to re-test our assumptions on this feature but in the meantime we > should default back to disabled. > Here is a performance run [with and without message > coalescing|http://cstar.datastax.com/graph?command=one_job&stats=9a26b5f2-7f48-11e6-92e7-0256e416528f&metric=op_rate&operation=2_user&smoothing=1&show_aggregates=true&xmin=0&xmax=508.86&ymin=0&ymax=91223] > -- This message was sent by Atlassian JIRA (v6.3.4#6332)